JAMB and WAEC Physics questions: Current electricity

34 questions with answers and explanations. Tap an option to check yourself.

1. Question 21· Current electricity· JAMB

   Ohm's law states that, at constant temperature, the current through a conductor is proportional to the

   • Aresistance
   • Bpotential difference across it
   • Clength of the conductor
   • Dtime

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   Explanation and discussion

2. Question 22· Current electricity· JAMB

   Resistors of 2 Ω, 3 Ω and 5 Ω are connected in series to a 20 V supply. Find the current.

   • A4 A
   • B2 A
   • C10 A
   • D1 A

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   Explanation and discussion

3. Question 23· Current electricity· WAEC

   Ohm's law applies to a metallic conductor provided its

   • Atemperature stays constant
   • Blength changes
   • Ccurrent is a.c.
   • Dcolour is the same

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   Explanation and discussion

4. Question 24· Current electricity· WAEC

   A potentiometer is preferred to a voltmeter for measuring e.m.f. because it

   • Ais smaller
   • Bis cheaper
   • Cdraws no current at balance
   • Dhas a scale

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   Explanation and discussion

5. Question 25· Current electricity· WAEC

   A wire of resistance 8 Ω is cut into two equal halves, which are then joined in parallel. Find the new resistance.

   • A8 Ω
   • B4 Ω
   • C16 Ω
   • D2 Ω

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   Explanation and discussion

6. Question 26· Current electricity· JAMB

   For a metal conductor, as its temperature rises, its resistance

   • Aincreases
   • Bdecreases
   • Cstays the same
   • Dfalls to zero

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   Explanation and discussion

7. Question 27· Current electricity· JAMB

   A copper wire is 10 m long with cross-sectional area 1 × 10⁻⁶ m². Find its resistance. (Resistivity of copper = 1.7 × 10⁻⁸ Ω m)

   • A0.17 Ω
   • B1.7 Ω
   • C0.017 Ω
   • D17 Ω

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8. Question 28· Current electricity· WAEC

   Find the combined resistance of 4 Ω and 12 Ω resistors connected in parallel.

   • A16 Ω
   • B3 Ω
   • C8 Ω
   • D48 Ω

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   Explanation and discussion

9. Question 29· Current electricity· JAMB

   Resistors of 2 Ω, 3 Ω and 6 Ω are connected in parallel. Find their combined resistance.

   • A1 Ω
   • B11 Ω
   • C0.5 Ω
   • D3 Ω

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10. Question 30· Current electricity· WAEC

    What current flows through a 20 Ω resistor when the p.d. across it is 6 V?

    • A120 A
    • B0.3 A
    • C3.3 A
    • D26 A

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    Explanation and discussion

11. Question 31· Current electricity· JAMB

    A wire of resistance R is replaced by a wire of the same material with twice the length and half the cross-sectional area. Its resistance is

    • A2R
    • BR
    • C4R
    • DR/4

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    Explanation and discussion

12. Question 32· Current electricity· JAMB

    The resistivity of a material depends on

    • Athe nature of the material and its temperature
    • Bits length
    • Cits cross-sectional area
    • Dthe current

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    Explanation and discussion

13. Question 33· Current electricity· JAMB

    A Wheatstone bridge is balanced with P = 4 Ω, Q = 6 Ω and R = 10 Ω. Find the resistance S.

    • A15 Ω
    • B6.7 Ω
    • C2.4 Ω
    • D20 Ω

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14. Question 34· Current electricity· WAEC

    The resistance of a wire is doubled when its

    • Atemperature falls
    • Barea is doubled
    • Clength is doubled
    • Ddiameter doubles

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    Explanation and discussion